1. Field of the Invention
The invention relates to direct printing. More particularly, the invention relates to a system and process for direct printing using conductive particles in an ink solution for dispersion on substrates, particularly traditional technology substrates that contain pre-provided electronic circuits, to create one or more new custom electronic functions.
2. Background Art
Printable electronic inks, and other new “paper-like” display technologies such as E Ink, have developed as an advanced processes of producing electronics and displays on paper-like materials and films. These low cost electronics promise to dramatically reduce costs and increase the number and variety of applications for electronics and displays into markets which were previously considered too costly. The phrase “disposable electronics” will now come to describe these type of low costs products, and actually be realizable. Examples of such “disposable electronics” include intelligent medical packaging, RFID tags, smart cards, and the like.
The problem for many of these applications, however, is that the active devices needed to make them functional (transistors, display components, electronic memory, logic circuits, RFID and radio circuits, and others) often require high precision patterning techniques, clean room environments and other special processes that make them cost prohibitive for regional manufacturing using conventional printing equipment. There have been attempts in the prior art to try to overcome the costs prohibitions. For example, in the silicon industry, application specific integrated circuits (ASICs) were developed. These ASIC's were pre-patterned with transistor devices (very often with as many as 10,000 to hundreds of thousands of transistors). Often larger functional logic blocks (like a processor or memory circuit) were included and these devices were then called “standard cells.” But, there was no practical way to combine the ASIC's and standard cells with printable electronic inks.
Ink jet (IJ) printing, screen printing and other printing techniques of silver ink and other conductors have been demonstrated. This is a relatively simple and standard process. IJ printing and more exotic patterning techniques have also been used to create transistors on flexible substrates as well. But to date, the printing of semiconductors and displays has required far more complex processes for either organic or inorganic semiconductor materials to be deposited and turned into a functional transistor or other logic devices. Making custom printed circuits on low cost substrates with these processes would therefore require the customer to have either a very complex and sophisticated process equipment with many layers patterned, or originate a custom design for each new device.
Furthermore, even with today's current printing techniques of ink jet printing, screen printing and other printing techniques of silver ink and other conductors, the ability to complete electronic circuits on previously partially fabricated printed circuit boards cannot be done. Manufacturers of printed circuit board devices, therefore, must painstakingly design and verify their designs for electronic circuits prior to manufacturing them on conventional printed circuit boards. The ability to make changes to the conventional printed circuit boards is extremely limited, time consuming, and therefore very expensive. Customizing the printed circuit boards once they have been manufactured and delivered practically impossible.
Still further, traditional electronics do not lend themselves to ready customization. To create new designs, as discussed above, takes a considerable amount of resources. It is very expensive and time consuming to modify or customize an existing electronic circuit on a traditional substrate. As a result, today's circuit manufacturers are failing to meet the needs of a substantial component of electronic manufacturers.
Thus, a need exists for printing on standard substrates that overcomes all of the above mentioned difficulties, as well as those not mentioned, and provide the advantages described in greater detail below.